Anonymising data is not anonymous data, nowadays many data providers are claiming that our data will be used anonymously by removing uniquely identifiable markers from the details they collect from us.
Unfortunately to de-anonymise data all that is needed is pointers that make you unique, take for example your GPS data which shows you travel to 5 addresses regularly but end up at a particular address for 10+ hours most days.
Using this data the data purchaser knows your location, cross checking this data will give the names on your street, checking names at each of the other streets and applying data from other purchasable sources for social connections across those locations will provide enough information to recreate who you are and who your friends / family are.
With the computational power available today using AI or ML routines, I would be surprised if the majority of “your”anonymous data is still anonymous once it is in the hands of the Data purchaser.
Food for thought?